DSS 330 Exam # 1 (Conceptual Definitions)

A Database is

an information model because it uses information to model something from the real world

Logical Database Components are

Entities and Atrributes

Entites

Anyone or anything we keep information on, instances

Attributes

describes and identifies entities; aka characteristics, measures, and dimensions

Physical Database Components

Servers and Data

Servers

powerful computers

Data

kept on computers

Centralized

in a single place, easier to maintain

Distributed

multiple locations, separate storage and processing, and makes users experience easier

Server Architecture

Data

Client Architecture

Application Software

A.C.I.D acronym defines

the reliability of a database

Atomicity in A.C.I.D

Transactions are all or nothing. Either the entire transaction occurs—or nothing occurs.

Consistency in A.C.I.D

Only valid data is saved

Isolation in A.C.I.D

transactions do not affect each other

Durability in A.C.I.D

written data will not be lost, transactions are permanent

Database Administrator (DBA) is

responsible for everything in a database. Ensure that a database is available as needed and is protected and secured from unauthorized users and activities

Database Management System (DBMS) Structure Diagram

a program through which users interact with the data stored in a database

Metadata is

Information about information

Schema is a

model or blueprint of the tables and relationships between the tables. Overarching organization of databases

A Relational Database is

a structure that contains data about many categories of information displayed in two-dimensional tables (relations)

Relational Data Model is made up of

Columns (fields) and Rows (records and tuples)

Columns in a table (relation) are often called

fields or attributes

Rows in a table (relation) are often called

records or tuples

Records are

a group of related fields (rows)

Table (aka File and Relation) is

a group of records

A database consists

of a group of tables

The entries in the table are Single-Valued meaning

each intersection of the row and column in the table contains only one value

Primary Key is

the column or columns that uniquely identify a single record

QBE (Query-By-Example) is

a visual GUI (graphical user interface) approach to writing queries.